Surgical excision of flat and protuberant skin lesions may involve cutting through the dermis about the periphory of the lesion with a stiff bladed scapel or other keen-edged tool held generally perpendicularly to the skin surface. Such deep incision of skin tissue produces bleeding and usually requires suture closure to induce primary intention healing of the wound. If such full-thickness dermal incision is not required to remove the lesion, an alternate, somewhat less traumatic, procedure involves tangential excision or horizontal slicing of skin tissue without cutting through the dermis whereby bleeding is avoided, or at least greatly reduced, and secondary intention healing of the wound can be expected.
Transverse or tangential excision of various skin lesions is commonly performed by dermatologists using an unaltered double-edged razor blade. The user typically places his thumb and index finger upon opposite end surfaces of the blade and squeezes the ends toward one another causing the blade to bow convexly away from the finger tips into a U-shape. With the blade gripped and compressed in this manner, it may be positioned at or near the periphory of a lesion; and, thereafter, the arcuate bottom of the blade is advanced relative to the lesion with a scooping or slicing action. The cutting technic employed by the user will vary depending on such considerations as the size, shape and type of lesion encountered and depending on the purpose of the procedure.
While the utilization of commercially available double-edged razor blades as a simple and effective means to accomplish tangential excisions is well known and widely employed by dermatologists, users recognize certain undesirable aspects of this practice. Principal among these is the risk of accidentally cutting fingers on the sharpened longitudinal edges of a blade. Obviously this risk is present as the blade is handled in preparing it for use, as for example, in cleaning it of the usual rust-inhibiting lubricant and in sterilizing the same. When the user grips the blade between his thumb and index finger, a marginal end of a sharpened edge may come into engagemant with the user's gloved finger or thumb; and, subsequent compression of the blade ends necessary to effect bowing of the blade body may cause this sharp surface to puncture the glove and pierce the skin. Such risk of accidental contact with the sharpened blade edges is especially great where the user's fingers are large and when the required squeezing force applied by the fingers is substantial.
As shown in FIGS. 2(a)-(d) of the drawings of prior art devices, the extremely thin end surfaces of the blade typically have intersecting edges forming corners which can penetrate both a surgical glove and subjacent skin unless the user has developed the skill to maintain a steady grasp of the blade while limiting the digital pressure on the blade ends to only the minimum required for correct blade flexing. This danger is exacerbated by the common practice among dermatologists of breaking a standard blade in half along its longitudinal centerline thereby increasing the flexibility of the surgical tool and also salvaging the unused blade edge for future use. The drawing presented herein of a prior art blade so broken clearly indicates that the broken ends include dangerously jagged surfaces to which the user's fingers are unavoidably exposed due to the drastic reduction in the extent of the gripping surfaces along the blade ends. Clearly an additional hazard is presented to an individual who undertakes to break a thin steel razor blade without appropriate safeguards.
From the foregoing it will be appreciated that the adaptation of a flexible razor blade as a surgical implement is dangerous to the user largely because a razor blade comprises a cutting tool which was never intended to be digitally grasped and manipulated. To the contrary, skin-incising devices such as scapels, scissors and dermatomes, for example, are provided with suitable handles or grips which position and help to maintain the user's hand and fingers some distance from dangerously sharp edges.
It is believed that, in order to fulfill the needs of professionals wishing to tangentially excise skin lesions, a special blade for this purpose should have these characteristics:
1. The cutting edge should be easily flexed by digital compression of the blade. PA1 2. The blade-gripping digits of the user should be adequately protected from inadvertent contact with all sharp blade surfaces. PA1 3. The gripping surfaces should be defined by the opposite end portions of the blade itself in order to retain to the user the greatest possible tactile sensitivity to the degree of curvature in the blade and to the reaction of tissue to the cutting motion of the blade. PA1 4. The gripping surfaces should be smoothly configured to avoid cutting or otherwise penetrating protective gloves worn by the user; and, these surfaces should provide handle means which aid the user in maintaining a secure grasp on the blade at points remote from any active cutting edge. PA1 5. The flexibility of the blade should be established by design and should be selectable over a substantial range to suit individual users in a variety of applications. PA1 6. The blade surface should be flat and smooth for ease of sterilization and packaging. PA1 7. The manufacturing cost of the blade should be about the same as a standard razor blade in order that a blade, once used, may be disposed of without concern as to replacement cost. PA1 1. The blade comprises a flexible, one-piece, flat body; PA1 2. The ends of the blade project from the body to shield the blade's cutting edge or edges; PA1 3. The blade ends provide safe and efficient finger grips; and, PA1 4. The cutting edges of the blade extend over less than the full length of the leading edge of the blade.
Some of the shortcomings of a standard razor blade when used as a transverse excision device are identified and addressed by the disclosure of U.S. Pat. No. 4,943,295 issued to Hartlaub on Jul. 24, 1990. Rather than proposing a novel blade specifically designed to correct such shortcomings, Hartlaub discloses a standard double edged razor blade having fairly thick, molded finger grips that are bonded to and encase its opposite end portions. Another sheath-like guard made of flexible plastic or rubber extends longitudinally between the finger grips and receives that sharpened blade edge not then being used for cutting. By enclosing the opposite ends and the unused edge of a razor blade in specially configured protective structures attached to the blade, Hartlaub has indeed reduced the opportunities for inadvertent contact with dangerous edges and corners. It will, however, be appreciated that Hartlaub's attempt to cure the many problems attributable to the misapplication of a razor blade as a flexible surgical tool by encasing the blade edges with his grips and sheath fails to meet the detailed criteria listed above and discussed further hereinbelow.